It is known that the triglyceride taken as food is generally hydrolyzed in intestine and the hydrolyzate is synthesized again to triglyceride as chyromicron in the intestinal wall, from where it moves to the liver via blood and lymph vessels and is then resynthesized to the various lipoproteins. Therefore. various lipoproteins are present in blood while maintaining a suitable concentration relation in the state of normal lipid metabolism. However, once the lipid metabolism becomes abnormal, the various lipoprotein concentrations increase to cause hyper lipemia resulting in various diseases.
It has heretofore been believed that these lipoproteins are decomposed by lipoprotein lipases and that the resulting fatty acids are incorporated in tissues. However, surprisingly, we have found that in rabbits fed with a high chlosterol diet for about six months there results fatty liver and hyper lipemia to high degree; and also the lipoprotein lipase activity was higher than in normal rabbits. Also in patients of hyper lipemia of Types II to IV according to Frederickson's classification of hyper lipemia, it appears that the activity of the lipoprotein lipase is not different from the activity in normal subjects. Thus, the question has existed as to why disorders in lipid metabolism occur even in the absence of an interference with the activity of lipoprotein lipase.